Drill bit



June 12, 1934. G. G. HARRINGTON DRILL BIT Filed March '7, 1932 Patented June 12,1934

UNITED STATES PATENT OFFICE DRILL BIT poration of Texas Application March 7,

2 Claims.

This invention relates generally to deep well drilling apparatus, and specifically to drill bits.

The conventional drill bit of the removable blade type includes a bolt or pin carried by the head and extending through an opening in the blade to hold the blade in a slot in the head. In deep Well drilling, the parts are subjected to great strains, and the bolt is either broken or loosened, so that it falls out of the head, and the blade is released. The drill stem must then be removed 0 from the hole, and the bolt and blade recovered by fishing tools before drilling can be continued.

To prevent the foregoing, this invention has for its object the provision of a drill bit of the removable blade type embodying new and improved means to hold the blade in place.

The preferred embodiment of the invention is illustrated by the accompanying drawing, of which Fig. 1 is a partly sectional side elevation of the bit; Fig. 2, a partly sectional side elevation at a right angle to Fig. 1; and Fig. 3, a bottom plan view.

The bit head is indicated at 1. It is connected to the lowermost secton of a drill stem, not shown. In its lower end it has a slot 2, the walls of which are inclined upwardly and inwardly, as shown; and a transverse bore 3 communicating with said slot.

Within the slot 2 is a blade 4 of the fish tail type, the upper portion of which is tapered to snugly engage the walls of the slot 2. The blade 4 has a pin opening 5, the upper portion 6 of which is larger than its lower portion 7.

In the bore 3 and extending through the opening 5 in the blade 4 is a pin 8 having a reduced central portion 9. This pin may be held in the bore 3 by threads 10 and a cotter pin 11. That portion 13 of the pin 8 in the bore 3 adjacent the opening 5 in the blade is stronger than that portion 12 of said pin in said bore remote from 1932, Serial No. 597,315

said opening so that if said pin is broken, it will fail at the portion 12 and the portion 13 will serve to hold the blade in the head.

It will be noted that the larger, upper portion 6 of the blade opening 5 is adapted to receive the threaded end 10 of the pin, and the smaller, lower portion 7 of the blade opening 5 is adapted to receive the reduced portion 9 of the pin. The pin 8 is passed through the bore 3 and the portion 6 of the blade opening, and the drill is then lowered into the hole. When the blade 4 engages the formation, it is forced upwardly into the slot 2 so that the reducedportion 9 of the pin 8 enters the smaller portion 7 of the blade opening 5.

As the ends of the pin cannot pass through the smaller portion 7 of the blade opening, the pin cannot fall out of the head.

I claim:

1. A bit head having a downwardly opening slot in its bottom, the walls of said slot being inclined inwardly and upwardly, and a transverse bore communicating with said slot; a blade having a tapered portion to fit in said slot, and an opening in said tapered portion, the upper portion of said opening being larger than the lower portion of said opening; and a pin movable into said bore and through said opening to hold said blade in said slot, said pin having a reduced portion between its ends to fit in the smaller portion of said blade opening.

2. A bit head having a downwardly opening slot in its bottom, and a transverse bore communicating with said slot; a blade having an opening, the upper portion of said opening being larger than the lower portion of said opening; and a pin movable into said bore and through said. blade opening to hold said blade in said slot, said pin having a reduced portion between its ends to fit in the smaller portion of said blade opening.

GEORGE G. HARRINGTON. 

